#10 support for session management

[Oswald Buddenhagen]

please add support for the windowing systems' session
management. under X, this would be XSMP. windows
has a different protocol, of course. unix command line
and dos obviously have no support for session
management, but there you don't want it anyway (ever
felt the desire to restore all your vts to the state you left
off? :).
you can use the api of qt or some other toolkit for
reference.
actually implementing the session management (reacting
to a pending shutdown, saving window status, options,
etc.) would be the application's task. there is enough
reference source code for this as well.